drbd: improvements to activate/deactivate multiple activity log extents

Recent commit drbd: get rid of bio_split, allow bios of "arbitrary" size
had a reference count leak: it only deactivated the first of several
activity log extents for intervals crossing extent boundaries.

This commit generalizes on bios spanning multiple activity log extents
in drbd_al_begin_io, and adds the necessary loop around lc_put in
drbd_al_complete_io as well.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 07f222c..50b851e 100644 (file)
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -209,20 +209,16 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
 {
        /* for bios crossing activity log extent boundaries,
         * we may need to activate two extents in one go */
-       unsigned int enr[2];
-       struct lc_element *al_ext[2] = { NULL, NULL };
-       struct update_al_work al_work;
+       unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
+       unsigned last = (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
+       unsigned enr;
 
        D_ASSERT(atomic_read(&mdev->local_cnt) > 0);
 
-       enr[0] = i->sector >> (AL_EXTENT_SHIFT-9);
-       enr[1] = (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
-       wait_event(mdev->al_wait, (al_ext[0] = _al_get(mdev, enr[0])));
-       if (enr[0] != enr[1])
-               wait_event(mdev->al_wait, (al_ext[1] = _al_get(mdev, enr[1])));
+       for (enr = first; enr <= last; enr++)
+               wait_event(mdev->al_wait, _al_get(mdev, enr) != NULL);
 
-       if (al_ext[0]->lc_number != enr[0] ||
-           (al_ext[1] && al_ext[1]->lc_number != enr[1])) {
+       if (mdev->act_log->pending_changes) {
                /* drbd_al_write_transaction(mdev,al_ext,enr);
                 * recurses into generic_make_request(), which
                 * disallows recursion, bios being serialized on the
@@ -239,8 +235,8 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
 
                /* Double check: it may have been committed by someone else,
                 * while we have been waiting for the lock. */
-               if (al_ext[0]->lc_number != enr[0] ||
-                   (al_ext[1] && al_ext[1]->lc_number != enr[1])) {
+               if (mdev->act_log->pending_changes) {
+                       struct update_al_work al_work;
                        init_completion(&al_work.event);
                        al_work.w.cb = w_al_write_transaction;
                        al_work.w.mdev = mdev;
@@ -264,24 +260,28 @@ void drbd_al_begin_io(struct drbd_conf *mdev, struct drbd_interval *i)
 
 void drbd_al_complete_io(struct drbd_conf *mdev, struct drbd_interval *i)
 {
-       unsigned int enr = (i->sector >> (AL_EXTENT_SHIFT-9));
+       /* for bios crossing activity log extent boundaries,
+        * we may need to activate two extents in one go */
+       unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
+       unsigned last = (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
+       unsigned enr;
        struct lc_element *extent;
        unsigned long flags;
+       bool wake = false;
 
        spin_lock_irqsave(&mdev->al_lock, flags);
 
-       extent = lc_find(mdev->act_log, enr);
-
-       if (!extent) {
-               spin_unlock_irqrestore(&mdev->al_lock, flags);
-               dev_err(DEV, "al_complete_io() called on inactive extent %u\n", enr);
-               return;
+       for (enr = first; enr <= last; enr++) {
+               extent = lc_find(mdev->act_log, enr);
+               if (!extent) {
+                       dev_err(DEV, "al_complete_io() called on inactive extent %u\n", enr);
+                       continue;
+               }
+               if (lc_put(mdev->act_log, extent) == 0)
+                       wake = true;
        }
-
-       if (lc_put(mdev->act_log, extent) == 0)
-               wake_up(&mdev->al_wait);
-
        spin_unlock_irqrestore(&mdev->al_lock, flags);
+       wake_up(&mdev->al_wait);
 }
 
 #if (PAGE_SHIFT + 3) < (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT)